Growing evidence suggest that patients with Type 2 diabetes often have poor adherence with prescribed medication. Clearly, patient adherence to pharmacologic therapy is crucial to achieving the goal of metabolic control and reducing the risk of cardiovascular disease (CVD), the primary cause of mortality among these patients. However, few interventions have attempted to improve medication adherence in diabetic patients. In clinical practice, adherence information is usually not available. As a result, physicians do not discuss medication adherence with patients routinely. To address this need, we propose to develop, implement and evaluate a novel and sophisticated method to assess patients' levels of adherence to their prescribed medications and communicate this information to their primary care providers at the time of their clinical encounter. The specific aims of the proposed project are to: (1) develop a computerized clinical decision support (CCDS) tool for primary care physicians to assist them in identifying, monitoring and addressing problems with medication adherence in their patients with Type 2 diabetes. This includes a computer program that objectively assesses patient medication adherence based on patient aggregate medication history from an electronic medical record system (EMR), and a web-based portal for patients to provide behavioral and psychological data that contributes to improper medication utilization. These data elements will be combined into an easy to understand table and graphic format that will generated by the CCDS at the time of the clinical encounter; (2) evaluate the accuracy of the data-driven algorithm developed by our group for measuring medication adherence and the feasibility and usability of the patient portal and the CDSS; and (3) pilot test this system in a single real-world clinical setting and evaluate how this CDSS affect patient outcomes. The two primary outcomes are: 1) patients' medication adherence, as well as changes in patient reported barriers to medication use, and 2) patient outcomes measured by HbA1c, LDL and blood pressure. The secondary outcomes are provider and patient attitudes about the system including overall satisfaction of the system. We will survey patients and providers at 3-month interval after the system implementation. The results from this study will form the foundation of R18 application designed to determine in a randomized clinical trial whether this CDSS can improve glycemic and CVD risk factor control in patients with Type 2 diabetes.